Teejay, as you seem to be interested in the watermark I created, I made this little tuto with the two methods that give the same result, so everyone will be able to enjoy it if needed.
For this tutorial, I tried to make a pdf but this format does not take into account the transparency in the method with a single photo! So I attach the link to the .afdesign file, to view it properly. Once on the site, click on the red button to access the file.
https://www.cjoint.com/c/LBpvNG1nn72Don't look too much in the layers, it's always a mess when there are elements copied and pasted several times on the same sheet.
EDIT:
Changed the file